Support utf-8 encoded comment field

[mayswind]

What version of this package are you using?
11.0.14

What problem do you want to solve?
Comment field in torrent files which generated in old application would not use utf-8 as default character encoding, and there files also have an extra utf-8 encoded field, like comment.utf-8. The comment field in these torrent files would have garbled characters by using parse-torrent (see the below screenshot).

What do you think is the correct solution to this problem?
Parse the comment content from the utf-8 encoding field first, like processing the name field.

Are you willing to submit a pull request to implement this change?
Yes

[ThaUnknown]

where did this happen in real-world cases?

[mayswind]

where did this happen in real-world cases?

Actually, I opened some old torrent files and found this problem. I think it's not a good idea to put those torrents here directly, so I made the a testcase file and put it to #178.